Virulence of Septoria Triseti and Fungicide Control of Leaf Mottle and Fusarium Seed Infection of Canary Seed (Phalaris Canariensis)
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VIRULENCE OF SEPTORIA TRISETI AND FUNGICIDE CONTROL OF LEAF MOTTLE AND FUSARIUM SEED INFECTION OF CANARY SEED (PHALARIS CANARIENSIS) A Thesis Submitted to the College of Graduate Studies and Research In Partil Fulfillment of the Requirements For the Degree of Master of Science In the Department of Plant Sciences University of Saskatchewan Saskatoon By Luisa Paulina Cholango Martínez © Copyright Luisa Paulina Cholango Martínez, June 2016 All rights reserved PERMISSION TO USE In presenting this thesis in partial fulfilment of the requirements for a postgraduate degree from the University of Saskatchewan, I agree that the libraries of this University may make it freely available for inspection. I further agree that permission for copying this thesis in any manner, in whole part or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my writing permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. DISCLAIMER Reference in this thesis to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the University of Saskatchewan. The views and options of the author expressed herein do not state or reflect those of the University of Saskatchewan, and shall not be used for advertising or product endorsement purposes. Request for permission to copy or to make other use of material in this thesis in whole or part should be addressed to: Head of the Department of Plant Sciences 51 Campus Drive, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5A8 i ABSTRACT Leaf mottle, caused by Septoria triseti, is the most important disease of canary seed (Phalaris canariensis L.) in western Canada and when severe it may cause reduction of canary seed yield. Understanding the host-pathogen interaction and the variation in virulence of the pathogen population is important for the development of durable resistance in canary seed cultivars. Recently, canary seed was approved as food for human consumption and identification of pathogenic fungal species on canary seed panicles is necessary to monitor seed quality. The objectives of this project were: 1) to evaluate variation for virulence among 27 isolates of S. triseti on Phalaris spp., 2) to identify the fungal species present on canary seed, and 3) to evaluate the effect of fungicides, application timings and canary seed genotypes on leaf mottle and fusarium seed infection of canary seed. Under controlled conditions, 24 Phalaris genotypes were evaluated for leaf mottle severity after inoculation with 27 isolates of S. triseti collected during 2005, 2013 or 2014. Differential interactions were detected in this study, which suggest that this patho-system follows the gene-for-gene model. Accession PI 189547 from Mexico was identified as resistant to 25 of the 27 isolates, which should be a valuable parent in a canary seed breeding program. Survey reports from 2014 and 2015 indicated the presence of Alternaria spp. and Fusarium spp. related to the FHB complex (Fusarium graminearum Schwabe, F. culmorum (W. G. Smith) Sacc., F. avenaceum (Corda ex Fr.) Sacc. and F. poae (Peck) Wollenw). A field study at Saskatoon and Indian Head during 2014 and 2015, using moderately resistant (PI 251274-3) and susceptible (Keet) canary seed genotypes, and three fungicides (propiconazole, prothioconazole + tebuconazole and pyraclostrobin + metconazole) applied at flag leaf and heading stages indicated that fungicide application reduced disease severity in years of high humidity, but application timing had little to no effect. Canary seed genotypes did not differ for leaf mottle severity or ii fusarium seed infection. Although these studies increased our knowledge of the interaction between S. triseti and canary seed, the benefit of fungicide applications were more difficult to measure. Thus, more research is needed to integrate this information into effective strategies to control leaf mottle and FHB in this crop. iii ACKNOWLEDGEMENTS I would like to acknowledge to my supervisor Dr. Randy Kutcher for his support of my graduate studies, for his comments and suggestions, and for giving me the opportunity to explore different areas during my program. A special thanks to Dr. Pierre Hucl for supporting the canary seed project. I want to thank all members of the Cereal and Flax Pathology group for their guidance in field and lab work, especially Jess Taylor and Tim Dament who taught me the first techniques at the beginning of my project. I want to thank all the people that were part of my life during my master’s program, those who I saw every day and shared a smile, a lunch and just a greeting because they gave me the energy to continue, and to my good friends for their support and friendship, Eliza, Anh, Christine, Mandeep and Mercedes. A big thank you to my lovely family, dad and mom, and my sisters Rebeca, Helen and my special Yasodhara, for the daily motivation and support. Thanks Paulette and Dorrin my homestay family here in this lovely city. iv DEDICATION To my beloved father and mother, my daily inspiration to be a better person and professional, who taught me the value of work hard, dreaming big and to be happy. v TABLE OF CONTENTS ABSTRACT ................................................................................................................................... ii ACKNOWLEDGEMENTS ........................................................................................................ iv DEDICATION .............................................................................................................................. v TABLE OF CONTENTS ............................................................................................................ vi LIST OF TABLE ......................................................................................................................... ix LIST OF FIGURES ..................................................................................................................... xi LIST OF ABREVATIONS ....................................................................................................... xiii CHAPTER 1 : ................................................................................................................................ 1 Introduction and research hypotheses ........................................................................................ 1 1.1 Introduction ......................................................................................................................... 1 1.2 Hypotheses and objectives: ................................................................................................. 3 CHAPTER 2: ................................................................................................................................. 5 Literature Review ......................................................................................................................... 5 2.1 Canary seed (Phalaris canariensis L.) ................................................................................ 5 2.1.1 Origin and classification ..................................................................................................... 5 2.1.2 Distribution of canary seed ................................................................................................. 6 2.1.3 Cytological and morphological characteristics ................................................................... 6 2.1.4 Nutrient composition of canary seed and uses .................................................................... 7 2.1.1 Agronomic characteristics ................................................................................................... 9 2.2 Insect pests and diseases of canary seed ........................................................................... 10 2.2.1 Septoria triseti Speg. ......................................................................................................... 11 2.2.2 Host range of Septoria triseti ............................................................................................ 12 2.2.3 Distribution and symptoms of leaf mottle ......................................................................... 12 2.2.4 Host-pathogen interactions................................................................................................ 13 2.2.5 Fusarium graminearum Schwabe ..................................................................................... 15 2.3 Yield losses in canary seed ............................................................................................... 15 2.3.1 Yield loss caused by Septoria spp. .................................................................................... 15 2.4 Fungicide control of Septoria spp. and FHB .................................................................... 16 2.4.1 Fungicide application timing to control Septoria spp. ...................................................... 16 2.4.2 Fungicide control of fusarium head blight .......................................................................